Question

我观看了WWDC会议，阅读了Swift上的新程序员，并阅读了Stack Overflow上我发现的所有相关问题。从Swift 1.2迁移到Swift 2.0后，我修复了应用程序中的大多数错误。

然而，还有一些我无法解决的问题。

向下倾斜AnyObject

错误：

不能从＆＃39; [AnyObject]＆＃39;更可选的类型＆＃39; [NSManagedObject]＆＃39;

代码：

    let fetchRequest = NSFetchRequest(entityName: formulaEntity)

    var error: NSError?

    do {
        let fetchedResults = try managedContext.executeFetchRequest(fetchRequest) as! [NSManagedObject]?

        if let results = fetchedResults {
            stocks = results
        } else {
            print("Could not fetch \(error), \(error!.userInfo)")
        }
    } catch {
        print("ERROR: \(error)")
    }

显示的错误发生在let fetchedResults = try...行

我的另一个奇怪的错误是在我的AppDelegate中：

错误：

＆＃39;的NSMutableDictionary＆＃39;不能转换为＆＃39; [NSObject：AnyObject]＆＃39;

代码：

    lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
    // Create the coordinator and store
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("Stocks.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    do {
        try coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
    } catch var error1 as NSError {
        error = error1
        coordinator = nil
        // Report any error we got.
        let dict = NSMutableDictionary()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict as [NSObject : AnyObject])
        // Replace this with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort()
    } catch {
        fatalError()
    }

    return coordinator
}()

我从未接触过上面的代码。所以我不知道为什么Apple的迁移工具没有正确迁移它。

我的AppDelegate中的另一个错误：

二元运营商＆＃39;＆amp;＆amp;＆＃39;不能应用于两个Bool操作数

通话可以抛出，但没有标记为＆＃39;尝试＆＃39;并且没有处理错误。

代码：

func saveContext () {
    if let moc = self.managedObjectContext {
        var error: NSError? = nil
        if moc.hasChanges && !moc.save() {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog("Unresolved error \(error), \(error!.userInfo)")
            abort()
        }
    }
}

我再次触及AppDelegate的这一部分，并且不确定上述代码到底出了什么问题。

Answer 1

似乎AppDelegate上的CoreData存在严重的Swift 2迁移问题。我能够通过将AppDelegate CoreData Swift 1.2完全替换为Swift 2.0来解决问题。

您需要做的是删除以下内容

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {

lazy var managedObjectContext: NSManagedObjectContext = {

// MARK: - Core Data Saving support

func saveContext ()

粘贴Swift 2.0代码：

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
    // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
    // Create the coordinator and store
    let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("SingleViewCoreData.sqlite")
    var failureReason = "There was an error creating or loading the application's saved data."
    do {
        try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
    } catch {
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason

        dict[NSUnderlyingErrorKey] = error as NSError
        let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        // Replace this with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
        abort()
    }

    return coordinator
}()

lazy var managedObjectContext: NSManagedObjectContext = {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
    let coordinator = self.persistentStoreCoordinator
    var managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
}()

// MARK: - Core Data Saving support

func saveContext () {
    if managedObjectContext.hasChanges {
        do {
            try managedObjectContext.save()
        } catch {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            let nserror = error as NSError
            NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
            abort()
         }
     }
 }
}

这应解决问题。

Answer 2

不能从'[AnyObject]'转发到更可选的类型'[NSManagedObject]'

在Swift 1.2中，executeFetchRequest(:_)返回[AnyObject]?。在Swift 2中，它返回[AnyObject]，因为新的try ...语法返回非可选。

（如果该方法返回nil，则该方法根本不会返回，并且控制将移至catch块。）

'NSMutableDictionary'不能转换为'[NSObject：AnyObject]'

这意味着您正在尝试将某些内容插入到无法转换为Objective-C对象的NSMutableDictionary中。在您的情况下，我认为这是因为error是符合ErrorType的结构，而不是NSError对象。请尝试添加error1。

调用可以抛出，但没有标记为'try'，并且未处理错误。

save()可能会抛出错误，因此需要使用try执行错误，而不是将其评估为bool。正如Martin R.在评论中指出的那样，this question的答案提供了一个完整的解决方案，所以我不会在这里重复它。

Swift 2.0迁移错误

2 个答案: